<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="/js/vue.js"></script>
    <style>
        .active{
            text-decoration: underline;
        }
        .text-danger{
            font-weight: bold;
        }
    </style>
</head>
<body>
    <div id="app">
        <div v-bind:class="[isActive?'active':,'text-danger']">Hello School!</div>
    </div>
    
</body>
<script>
  var vm = newVue({
    el:'#app',
    data:{
        isActive:true
    }
  })
</script>
</html>